1. Technical Field
The present invention generally relates to engine control systems for automotive vehicles and, more particularly, to a method of improving drivability during acceleration based on a fuel multiplier.
2. Discussion
Recent advances in automotive vehicle engine control systems have led to the development of dynamic crankshaft fueling control systems. For instance, commonly assigned U.S. patent application Ser. No. 08/901,859, entitled "Method for Processing Crankshaft Speed Fluctuations for Control Applications" filed Jul. 29, 1997, now U.S. Pat. No. 5,809,969, which is hereby expressly incorporated by reference herein, discloses one such dynamic fueling control system. According to this system, the amount of fuel delivered to the engine is reduced to obtain superior catalyst light off and engine out hydrocarbon reduction. However, if acceleration is demanded while the dynamic fueling control system is active, the typical amount of acceleration enrichment applied during throttle tip-in is insufficient to achieve optimum engine performance. Thus, with the standard acceleration enrichment, a lean tip-in sag condition exists while the dynamic fueling control system is active. From a calibration stand-point, this trend is particularly noticeable when 1300 drivability index fuel is used.
In view of the foregoing, it would be desirable to provide a system for enhancing the level of acceleration enrichment applied during a throttle tip-in event when an associated dynamic crankshaft fuel control system is active.